Bagaimana Cara Mengatasi Eror Tanggal yang tidak terdefinisi

<?php
if (isset($_POST['submit']))
{
	include "./include/confiq.php";
	@$tanggal=date("Y-m-d");
	@$produk=htmlentities($_POST['produk']);
	@$harga=htmlentities($_POST['harga']);
	@$jumlah=htmlentities($_POST['jumlah']);
	@$url=htmlentities($_POST['url']);
	@$file="./admin/gambar/$url";
	@$ket=htmlentities($_POST['keterangan']);

	if ($produk=="" or $harga=="" or $jumlah=="" or $ket="")
	{
		echo "<script> document.location.href='home.php?page=7&status=<font color=red>Gagal! Lengkapi Data..</font>'; </script>";
	}else{
		$query=mysql_db_query($db,"insert into produk values('','$tanggal','$produk','$ket','$harga','$jumlah','$file')",$koneksi);
		if ($query)
		{
			echo "<script> document.location.href='home.php?page=3&status=Success....'; </script>";
		}
	}
}else{
	unset($_POST['submit']);
}
?>